Double Vision

What

If you see two of whatever you are looking at simultaneously, you may have a condition known as double vision, referred to medically as diplopia. Double and blurred vision are often thought to be the same, but they are not. In blurred vision, a single image appears unclear and fuzzy. In double vision, two images are seen at the same time, creating understandable confusion for anyone who has it.

Cause

There are 2 of possible causes.

  1. Refractive – Light from an object is split into two images by a defect in the eye’s optical system. Cataracts might, for example, cause such a defect.
  2. Failure of both eyes to point at the object being viewed, a condition referred to as “strabismus” or “squint”. In normal vision, both eyes look at the same object. The images seen by the two eyes are fused into a single picture by the brain. If the eyes do not point at the same object, the image seen by each eye is different and cannot be fused. The result is double vision possibly caused because of a defect in the muscles which control the movement of the eyes or in the control of these muscles through the nerves and brain.

Implication

Double vision can be extremely discomforting. The brain acts to alleviate the discomfort by suppressing, or blanking out, one of the images. In young children, if this suppression persists over a continued length of time, it can lead to an impairment of the development of the visual system. The suppressed eye may get to the point where it is unable to see well, no matter how good the spectacle or contact lens correction a condition called amblyopia. Since it is a result of a defect in the interpretative mechanisms of the eye and brain, it is more difficult to treat than a refractive condition (one having to do with the eye’s ability to bend light).

Treatment

Treatment of double vision may consist of eye exercises, surgical straightening of the eye or a combination of the two. Therapy is aimed at re-aligning the squinting eye where possible without surgery and re-stimulating the part of the visual pathway to the brain, which is not working correctly.

Double vision can occasionally develop in a person who has never had the problem before due to trauma to the head or a problem with the nerve supply to the muscles around the eye. This type of ‘sudden onset diplopia’ can be a sign of a serious problems with the visual system so if you are experience any of the symptoms above, contact us immediately and make an emergency appointment with any of our optometrists.

If you need any further advice, please contact Ian Cameron.

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